VMware's willingness to dump two long-running aspects of the Windows interface in favor of a Mac-like take on them is evidence of the company's competitive relationship with Microsoft. Though dependent upon Windows for Fusion, VMware competes heavily with Microsoft in the virtual desktop infrastructure and server virtualization markets.

"Microsoft makes it a practice not to comment on products we haven't seen," a company spokeswoman said via e-mail.

Dan Englander, a Web designer in Concord, Mass., who has been beta-testing Fusion 3.0, said in a blog post that "Fusion 3.0 seems faster and more responsive than 2.0." Windows' Aero graphical desktop "runs well," while the Unity feature allows Windows apps to show up on the Mac dock, ready to be launched, he said.

Available Oct. 27, five days after the release of Microsoft's Windows 7 operating system, Fusion 3.0 will also run Windows on a Mac faster and more efficiently than prior versions of Fusion. For instance, an idle virtual machine of Windows 7 under Fusion 3.0 will only use about 5% of the processor's power, Lee said.

Lower CPU utilization means lower power usage, Lee said, and addresses the complaint that running Windows under Fusion quickly drains the MacBook battery. Lee said he can run Windows' Outlook e-mail via Fusion 3.0 on his MacBook Pro for as long as four hours.

"I feel we've made good progress on reducing overhead," he said, adding that Fusion 3.0 will be more efficient with Windows 7 and XP than it was with Vista.

Available immediately for pre-order, Fusion 3.0 lists for $79.99 for a full retail copy, and for $39.99 for an upgrade.

Fusion 3.0 will apparently beat rival Parallels 5.0 to the market. Parallels Inc. did not respond to a request for comment. In beta now, Parallels 5.0 will reportedly also feature support for Aero and faster, more efficient performance.

Fusion 3.0 will have enough support for the DirectX 9.0c and OpenGL 2.1 multimedia APIs to enable users play Windows action games such as Portal or Lego Star Wars on Macs, said Lee. Fusion 3.0 will also let viewers watch 1080p video, as did Version 2.

To support those games and Windows graphical features such as Aero, Lee said, Mac hardware with an ATI Radeon 2600 or Nvidia 8 series graphics chip will be needed. One or the other came standard on all Macs in the past two years, he said.

Fusion 3.0 also lets users migrate their copies of Windows on a PC into virtual machines running on a Mac more easily. OEM versions of Windows that came pre-installed on a PC, however, are not eligible to be migrated to a Mac, according to Microsoft licensing rules, Lee said.

Citing data from research firm NPD Group Inc. on U.S. retail sales of Fusion since its first release in August 2007, Lee said that Fusion leads Parallels with a market share of just over 50%. A number of companies and schools have bought 4,000 copies of Fusion, Lee said, although he declined to name them.